根據(jù)https://developer.android.com/training/notify-user/badges 從 Android 8 開始，操作系統(tǒng)允許設(shè)置應(yīng)用程序圖標(biāo)通知徽章，但我無法讓它工作。            NotificationManagerCompat nm = NotificationManagerCompat.from(activityContext);            if (Build.VERSION.SDK_INT >= 26) {                NotificationChannel nc = new NotificationChannel("ab", "chanelName", NotificationManager.IMPORTANCE_DEFAULT);                nc.setDescription("A chanel description here");                nc.setShowBadge(true);                NotificationManager nmm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);                nmm.createNotificationChannel(nc);            }            NotificationCompat.Builder nb = new NotificationCompat.Builder(App.instance, "ab");            nb.setSmallIcon(R.drawable.accept_icon);            nb.setTicker("here is the ticker");            nb.setContentText("Here content text");            nb.setContentTitle("Here content title");            nb.setNumber(5);            nb.setBadgeIconType(NotificationCompat.BADGE_ICON_SMALL);            nm.notify(1, nb.build());我正在使用 Nexus 6P 和 android 8.1 。它在系統(tǒng)欄中顯示通知，但不在應(yīng)用程序圖標(biāo)上顯示徽章。我錯(cuò)過了什么？